Typically, lamps used for general lighting utilize a tungsten filament that is heated to generate light. This process, however, is generally inefficient because a significant amount of energy is lost to the environment in the form of extraneous heat and non-visible, infrared and ultraviolet, radiation. Other alternatives for general lighting include fluorescent lamps and light emitting diodes. While more efficient than incandescent lamps having tungsten filaments, fluorescent lamps tend not to have pleasing spectral characteristics, and light emitting diodes tend to be expensive.
It has been known for at least a century that electrons accelerated by high voltage in vacuum, otherwise known as cathode rays, can cause compounds known as phosphors to emit light when they strike those compounds. Much cathode ray tube (CRT) effort over the last century has been aimed towards apparatus using tightly focused, deflectable, electron beams for use in television, radar, sonar, computer, oscilloscope, and other information displays; these devices are hereinafter referenced as data display CRTs. CRTs have not generally been used for general lighting.
Data display CRTs typically operate with deflection circuitry for steering their electron beams and have such tightly focused electron beams that operation without deflection may “burn” their phosphor coating causing permanent damage. Such CRTs often, but not always, are operated by high voltage power supplies linked to their deflection circuitry.
Voltage multipliers driven by inverters have been used to provide the high voltage required to accelerate electrons in data display CRTs. For example, U.S. Pat. No. 5,331,255 describes a DC-to-DC converter having an inverter operating at about 1 MHz driving a Cockroft-Walton voltage multiplier to produce high voltage for driving a small data display CRT.
Many homes, businesses, and appliances have been wired with triac-type and similar dimmers. These dimmers block a user-adjustable portion of an alternating current waveform. Triac dimmers typically work well with incandescent lighting and other resistive loads, reducing light intensity or heat output by reducing an on-phase of each AC cycle, but typically do not work well with electronic loads such as compact fluorescent lamps.
Electronic loads such as many compact fluorescent lamps also tend to draw current as spikes almost exclusively at voltage peaks of the incoming AC waveform. These current spikes cause these loads to have a poor “power factor”, and can cause inefficiencies in a power system.